Robot systems or telemanipulators for minimally invasive surgery, particularly for laparoscopic surgery, replace the surgical instruments usually operated manually by the surgeon, e.g. surgical instruments, endoscopes, or camera, with a motorized positioning mechanism. The surgical instruments to be used are guided inside a patient's body via one or several trocars. A trocar refers to an instrument used by the surgeon in minimally invasive surgery to gain access to the patient's body cavity (usually the abdomen or thorax), whereby the port is kept open by a tube, a so-called tubus. The robot system provides a moving mechanism and control logic, which allows for the movement of the surgical instruments about a pivot point in 2 degrees of freedom (x, y) and a translational movement of the surgical instruments along the axis of the instrument (z). The pivot point refers to the invariant point of the motion in 2 degrees of freedom (x, y). This pivot point is ideally located at the point where the trocar penetrates the patient's abdominal wall. The control logic of a robot system must know the pivot point or the pivot point must be defined by the moving mechanism's design, to limit the surgical instrument's movement in a way that keeps the biomechanical stress acting on the tissue around the trocar at a minimum.
Robot systems known from prior art are based on robot arms for passive prepositioning and active moving of a surgical instrument. A solution based on prior art robot arms, which implement passive prepositioning and active moving of surgical instruments about a pivot point, requires a large installation space on the one hand and the motion sequences of the robot arms can lead to a collision on the other hand.
During a minimally invasive surgical procedure a minimum of two, usually three to four surgical instruments, such as gripper, scissors, needle holder, dissector, as well as a camera or an endoscope are used, which are each inserted into the patient's body via a separate trocar. This means that there is a robot arm for each employed surgical instrument, controlling the passive prepositioning and active moving of the instrument.
The disadvantage of the prior art solutions lies in the fact that the position of the patient has to be fixed before surgery commences and that repositioning the patient during surgery is near impossible. Another disadvantage already mentioned is the large installation space existing robot systems require.